Data Source

The weather maps shown here are generated from the
NCEP Global Forecast System (GFS) model. GFS is the primary operational model framework underlying U.S. NOAA/NWS
weather forecasting. The model is run four times daily on a global T1534 gaussian grid (~13 km) to produce 16-day
forecasts. Here, we use 0.25°x0.25° (~30 km) output grids available from
NOMADS, and calculate daily averages from eight 3-hourly timeslices starting at 0000 UTC.

Additional Details

Sea surface temperature (SST) and SST anomaly maps are generated from
NOAA Optimum Interpolation SST version 2 (OISST V2).
OISST is a 0.25°x0.25° blendend dataset derived from satellite, ship, and buoy measurements. The SST anomaly
is based on a 1971-2000 NOAA climatology.

Temperature refers to air temperature at 2 meters above the surface. The temperature anomaly is made in
reference to a 1979-2000 climatology derived from the
reanalysis of the NCEP Climate Forecast System (CFSR/CFSV2) model. This climate baseline is used instead of the
1981-2010 climate normal because
it spans a period prior to significant warming of the Arctic beyond historically-observed values. For context,
see this timeseries plot showing how various
climate baselines compare against the NASA GISS
1880-2014 global land-ocean temperature index.

GFS Model Bias Correction — GFS has a systematic model bias compared to CFSR/CFSV2 in which the diurnal
cycle has greater amplitude over areas of snow/ice and hot desert. A correction term, calculated from the difference
between GFS and CFSR/CFSV2 on average per month from June 2015 - May 2016, is therefore applied such that
regional temperature anomaly values are consistent with CFSR/CFSV2. A timeseries plot showing the bias corrections
for each region is shown here. Temperature anomaly maps showing uncorrected and corrected GFS vs. CFSR/CFSV2 can also
be found
here.

Note that bias-corrected GFS-CFSR temperature anomalies will still differ slightly from those calculated from
CFSV2-CFSR. The most reliable temperature anomaly estimates can be found in the
Daily Reanalysis Maps image archive.
The archive is updated once or twice per month.

Climate Reanalyzer

This website is produced by the
Climate Change Institute
at the University of Maine.
Our institute has more than a 40-year history of polar exploration, and research
contributions to glaciology, climate science, and anthropology.

Climate Reanalyzer utilizes and provides access to existing publicly-available
datasets and models. Original data sources are provided on the
Available Datasets page.

How to Reference

Please cite both original
data sources and Climate Reanalyzer for any data or images from this website appearing in
journal publications. Suggested journal reference: